1. Field of the Invention
The present invention relates to a substrate-transporting device, and more particularly to a substrate-transporting device for large-sized glass substrates.
2. Description of Related Art
In a fabricating process for liquid crystal display devices, a glass substrate is carried from a workplace to a fabricating apparatus by means of a transporting system such as a conventional system of a supporting fork and robot arm as shown in FIG. 1a. Recently, to reduce the fabrication cost of the liquid crystal display devices, it has been necessary to adopt large-sized glass substrates. Furthermore, to cooperate with such large-sized glass substrates, the way that the glass substrates enter the fabricating apparatus has been changed. A horizontal-type design to transport the glass substrates horizontally to the apparatus is generally used for the fabricating apparatus for small-size substrates. However, to efficiently utilize the space of a clean room, some of the fabricating apparatuses adopt a vertical-type design. Hence, the large-sized glass substrates tend to enter the apparatus in a vertical or tilted manner. As such, the conventional way using either the supporting fork or robot arm has encountered many technical difficulties. These technical difficulties are described as follows:    (1) A defect that occurs at the edge of the glass substrate fails to be detected. As shown in FIG. 1b, a supporting fork 100 has a small supporting surface so that it can't sufficiently cover the edge of a large-sized glass substrate 200. Thus, cracking defects 210 of the glass substrate cannot be effectively detected. These defects generally occur at the edge of the glass substrate. A large-sized glass substrate having such a defect would cause fragmentation when it is delivered into the fabricating apparatus. Once the fragmentation occurs, a large quantity of the glass fragments will stop the apparatus, and also, delay the fabrication process. In some serious cases, the fragments even will cause major damage to the apparatus.    (2) The fragments tend to easily occur when the glass substrate is transported into a loader of the fabricating apparatus adopting the vertical-type design. Because the conventional supporting fork is unable to position and align the posture of the glass substrates precisely, an auxiliary aligning mechanism is necessary to be mounted on the loader of the fabricating apparatus. This positioning issue can be easily solved for the small-size substrates and the horizontal-type fabricating apparatus. However, a slight deflection occurring somewhere in the large-sized substrates will accumulate and turn into an evident deflection at another position in the large-sized substrates. On the other hand, the glass substrate is not stably held by the loader of the vertical-type apparatus, so a cover plate or another protecting mechanism is provided to avoid the substrate from falling. Hence, the entrance is limited in size. Even if there is an alignment mechanism for the loader, the transporting system such as the fork will need to increase the precision of the position and posture alignments of the glass substrate. As a result, the conventional ways such as the supporting fork tend to cause the fragmentation.    (3) With the introduction of the fifth generation fab, both the horizontal type and vertical type fabricating apparatuses are applied and arranged randomly to a single production line. Hence, there is a dire need to provide a single transporting system capable of transporting glass substrates to either the horizontal type fabricating apparatus or the vertical type fabricating apparatus. So far, various transporting systems are used in fabricating process. Thus, the maintenance cost and time of these various transporting systems as well as the fabrication cost are all increased.
Therefore, it is desirable to provide an improved substrate-transporting device to mitigate and/or obviate the aforementioned problems.